Reverse osmosis is a point-of-use drinking water system. Household pressure forces water against a semi-permeable membrane; water molecules pass through, most dissolved solids do not, and the concentrated remainder goes down the drain. What comes out is stored in a small tank under the sink and delivered through a dedicated tap.
It is the most thorough residential treatment available for dissolved contaminants — and it is deliberately a one-tap solution, because treating an entire house to that standard would be enormously wasteful and unnecessary for showering, laundry and irrigation.
What reverse osmosis actually means
A typical under-sink RO system is a sequence, not a single filter. Water passes a sediment pre-filter, then a carbon pre-filter (which protects the membrane from chlorine, which damages common membrane materials), then the RO membrane itself, into a pressurised storage tank, and finally through a carbon post-filter that polishes taste on the way to the tap.
RO is measured by what it rejects. It substantially reduces total dissolved solids — the general measure of dissolved minerals and salts in water. Because it works on dissolved material rather than particle size, it addresses a much broader range of contaminants than a carbon filter alone.
The trade-offs are real and worth stating plainly: RO produces water slowly, stores it in a tank, sends some water to the drain in the process, and removes beneficial minerals along with everything else. Systems can be fitted with a remineralisation stage if the flat taste of demineralised water bothers you.
Symptoms you might be seeing
- Buying bottled water for drinking and cooking because the tap water does not taste right
- A persistent salty, metallic or mineral taste that carbon filtration has not resolved
- High total dissolved solids on a water test
- Coffee, tea and ice that taste of the water rather than of the drink
- An existing RO system that has gone slow, tastes off, or runs the tank empty quickly
- A drain line that trickles constantly, which usually means an RO fault rather than normal operation
What causes it
Naturally high dissolved mineral content
Groundwater in carbonate formations carries dissolved minerals as a matter of geology. That shows up as a mineral taste and a high TDS reading even when the water fully meets every applicable standard.
Softened water taste
Ion exchange trades hardness minerals for sodium. Some households notice that and want their drinking tap treated further. A point-of-use RO downstream of the softener is the usual answer.
Disinfection by-product taste
Treated municipal water can carry taste characteristics from disinfection. Carbon handles much of this; RO handles more of it, along with dissolved material carbon leaves behind.
Well water with elevated TDS
A private well delivers whatever the formation carries. Where TDS is high, point-of-use RO is often the most practical way to get good drinking water without over-treating the whole house.
How we inspect and diagnose it
- Measure total dissolved solids at the tap you intend to treat, and again on any existing RO output to see whether the membrane is still performing.
- Measure static water pressure. RO membranes need adequate pressure to work; below roughly 40 psi, output drops off and a booster or permeate pump may be needed.
- Test for chlorine residual, because unprotected exposure to chlorine will damage the common thin-film composite membrane and shorten its life dramatically.
- Check hardness. Feeding a softener's output to an RO membrane generally extends membrane life; feeding hard water to one shortens it.
- Inspect the under-sink space, drain arrangement and countertop or sink deck for a dedicated tap position.
- On an existing system, check pre-filter age, storage tank air pressure and whether the automatic shut-off valve is holding — a failed shut-off is the usual cause of a permanently running drain line.
What happens after you get in touch
- We test your waterTDS, hardness, chlorine and pressure at the point you want treated — the four numbers that decide whether an RO system will perform well in your house.
- We diagnose the taste or quality complaintSome drinking-water complaints are solved more cheaply with carbon, and some are caused by the plumbing rather than the water. We establish which before recommending RO.
- We recommend and configure the systemStage count, whether a booster or permeate pump is needed for your pressure, whether remineralisation makes sense, and where the tap and drain will go.
- We install and verifyWe install the manifold, tank, drain saddle and dedicated tap, flush the system through as the manufacturer requires, then measure TDS on the finished water so you can see the actual reduction rather than take it on trust.
Repair or replace?
Pre-filters and post-filters are consumables. Replacing them is routine maintenance, not a repair, and skipping it is the most common reason a system underperforms.
A membrane that no longer rejects properly — verified by comparing feed TDS to product TDS — is replaced rather than cleaned in a residential setting.
Individual components are commonly repairable: the automatic shut-off valve, the check valve, the tank bladder, the faucet, and leaking quick-connect fittings are all serviceable parts.
Whole-system replacement is worth considering when the manifold is a discontinued proprietary design with no filter availability, when fittings have become brittle, or when the household's needs have changed enough that a different configuration makes more sense.
Slow production is much more often a low-pressure or exhausted-pre-filter problem than a dead membrane. Diagnosing the difference is a five-minute test and can save a needless membrane purchase.
Equipment and materials involved
Sediment and carbon pre-filters
Protect the membrane from particulate and from chlorine. These are the stages that get changed most often, and they are what keeps the expensive stage alive.
RO membrane
The stage that does the actual separation. Rated by daily production capacity and by rejection percentage; both matter when matching a system to a household.
Pressurised storage tank
Holds treated water so you get useful flow at the tap. Tank air pressure has to be correct or the tank will seem full but deliver very little.
Dedicated faucet
A separate air-gap or non-air-gap tap on the sink deck. Local plumbing requirements determine which is appropriate.
Booster or permeate pump
Used where incoming pressure is marginal. Improves both production rate and the efficiency of the drain ratio.
Remineralisation cartridge
An optional post-stage that adds a small amount of mineral back for taste and pH. Purely an aesthetic preference — some households prefer the flat taste of pure RO water.
What affects the cost
We do not publish prices for this work, and we would be making them up if we did — the same service can differ substantially between two houses on the same street depending on the water and the plumbing. What we can be specific about is what moves the number:
- Number of stages and whether remineralisation is included
- Membrane capacity, which is matched to how much drinking and cooking water the household actually uses
- Whether a booster or permeate pump is needed because of low incoming pressure
- Whether an existing dedicated tap hole exists or a new one has to be created in the sink deck or countertop — stone countertops are a meaningful factor here
- Whether the system feeds only a tap or also a refrigerator or ice maker, which adds a run of tubing and sometimes a pump
- Drain connection type and whether an air gap faucet is required
- Ongoing cost of pre-filters and periodic membrane replacement
You get a figure after the test and the site visit, when there is something real to base it on.
How long it takes
- A standard under-sink installation with an existing tap hole is normally completed in a single visit.
- Adding a tap hole to a stone countertop takes longer and needs the right tooling.
- Running a line to a refrigerator or ice maker adds time depending on how accessible the path is.
- The system must be flushed through before use, and the first tank of water is discarded per the manufacturer's instructions — so 'installed' and 'ready to drink' are a few hours apart.
Keeping it working
- Replace sediment and carbon pre-filters on schedule. Most residential systems are on roughly an annual cadence, but heavy use or dirty feed water shortens it.
- Change the post-filter with the pre-filters; it is what your water tastes like on the way out.
- Check membrane performance by comparing feed TDS to product TDS rather than by calendar age. A membrane that still rejects well does not need replacing.
- Check storage tank air pressure with the tank empty; a soft tank is the most common cause of 'my RO ran out of water'.
- Sanitise the system when filters are changed, since the wet interior is exposed during service.
- Listen for a drain line that runs continuously — that is a fault, not normal operation, and it wastes a lot of water quietly.
Most of the failures we are called out to were preventable. Scheduled maintenance and filter replacement is the cheapest part of owning any of this equipment.
Limitations and realistic outcomes
- RO treats one tap. It is not designed to supply showers, laundry or irrigation, and sizing it to do so is impractical for a residential system.
- The process sends a portion of the feed water to the drain. Efficiency varies with pressure, temperature and system design, but there is always a reject stream.
- Production is slow and buffered by a tank. Draw the tank down and you wait for it to refill.
- RO removes beneficial minerals along with everything else, which is why remineralisation exists as an option. This is a taste and preference issue, not a safety one.
- A membrane's rejection performance is specific to the contaminant. We will not claim a system removes a particular contaminant to a particular level without the manufacturer's certified performance data for the exact system installed and a test showing what is actually in your water.
- Chlorine damages standard membranes. An RO installed without adequate carbon pre-treatment on chlorinated water will lose performance far earlier than it should.
North Port considerations
North Port households on city water most often ask about RO because of taste rather than because of a specific contaminant — treated water that meets every standard can still taste of its minerals and its disinfectant. RO is the point-of-use answer to that, and it pairs naturally with a whole-house carbon filter that protects the membrane.
North Port homes on private wells are a different conversation. There, RO is usually the last stage of a longer treatment train rather than a standalone purchase, because sediment, iron or hydrogen sulfide will destroy an RO system's pre-filters in short order if they are not dealt with upstream. We look at the whole train before quoting an under-sink unit.
More about water treatment in North Port, FL →
Port Charlotte considerations
Port Charlotte's municipal supply is treated and chlorinated, which makes carbon pre-treatment essential to membrane life — an RO installed here without adequate carbon protection will underperform within a year. We size the carbon stage for the measured residual rather than fitting a generic cartridge.
A large share of Port Charlotte's housing stock is single-storey homes with straightforward under-sink cabinets, which usually makes installation simple. The two things worth checking early are whether the sink deck already has a spare hole for a dedicated tap, and whether the customer wants the refrigerator ice maker fed from the system, since that decision changes the layout.
More about water treatment in Port Charlotte, FL →
In short
A reverse osmosis system pushes water through a semi-permeable membrane under pressure, separating out a large share of dissolved solids and sending them to the drain. It is a point-of-use system, normally installed under a kitchen sink with its own tap, and produces water for drinking and cooking rather than for the whole house. Pre-filters typically need replacing annually and the membrane less often.
Frequently asked
Does an RO system waste water?
It sends a portion of the feed water to the drain as a concentrate stream — that is inherent to how the membrane works. How much depends on incoming pressure, water temperature and system design, and a permeate pump can improve it considerably. For a point-of-use drinking system, the volume involved is small relative to household use.
Do I need a softener as well as an RO system?
They do different jobs. RO treats one tap for drinking and cooking; a softener treats the whole house for scale. If your complaint is drinking water taste, RO alone may be enough. If you also have scale on fixtures and appliances, RO will do nothing about it. Where both are installed, feeding softened water to the RO generally extends membrane life.
Why is my RO faucet slow?
Most often low storage-tank air pressure or exhausted pre-filters, not a failed membrane. Both are quick to check. Low incoming household pressure is the third common cause, and that one is solved with a booster or permeate pump rather than a new membrane.
Is RO water safe to drink long term?
RO water is widely used for drinking. It has fewer dissolved minerals than tap water, which some people notice as a flatter taste — a remineralisation cartridge addresses that if you prefer. Dietary mineral intake comes overwhelmingly from food rather than water, and we would refer any health-specific question to your physician rather than answer it as a water-treatment company.
Can I connect the RO to my refrigerator?
Usually yes, with a tubing run from the RO manifold to the fridge. Two things to plan for: the extra draw on tank capacity, and the run length, since a long line to a distant fridge can slow ice production. It is best decided before installation rather than added later.
Photos of this work
Real reverse osmosis installations from North Port and Port Charlotte will be shown here. We don't use stock or competitor images.
Related services
Whole-house filtration · Water softeners · System maintenance
Where we do this work
Reverse osmosis in North Port · Reverse osmosis in Port Charlotte